The proposed research will show that three important features of alcoholism can be demonstrated and studied in infrahuman subjects. First, ethanol when taken orally can be established as a reward or positive reinforcer (previously we have repeatedly demonstrated that ethanol can come to serve as a reinforcer for rats and rhesus monkeys). Second and third, in monkeys for when ethanol acts as a reinforcer, tolerance and physical dependence will be shown to reliably occur under certain conditions, such as continuous access to ethanol. Another objective will be to determine with monkeys the importance of food deprivation in maintaining ethanol-reinforced behavior. A final objective will be to show that simple procedues developed in our laboratory can be reliably used to establish ethanol as a reinforcer for various strains of rats and two species of monkeys. In all these studies the methods and principles of operant conditioning will be used.